Portsmouth has an exceptional restaurant scene for a city of its size. The concentration of good cooking within a few blocks of Market Square regularly draws diners from Boston, an hour and a half south. The emphasis is on seafood from local waters — lobster, clams, oysters from the Great Bay estuary — alongside modern American menus that use the same sources.
Black Trumpet Bistro on Ceres Street is the standard-bearer: a serious wine list, a menu that changes with the season, and cooking that would be unremarkable in a much larger city and is startling in a New Hampshire seaport. The street-level space is more casual than the basement dining room. Jumpin' Jay's Fish Café on Congress Street is the best pure fish restaurant in the city — straightforward preparations of excellent local fish without fuss. Row 34 in the old Portwalk development has an extensive raw bar with oysters from the Great Bay and points north.
For something quicker, The Portsmouth Brewery on Market Street serves respectable pub food alongside its own beers; the chowder is reliable and the patio gets afternoon sun.